#define _CRT_SECURE_NO_WARNINGS 1
#include <iostream>
using namespace std;

long long sum = 0;
int n;
int main()
{
	cin >> n;
	for (int i = 1; i <= n/2; ++i)
	{
		sum += n / i;
	}
	sum += n - n / 2;

	cout << sum << endl;

	return 0;
}